WO1997037761A1 - Catalyseur d'epuration de gaz d'echappement et procede d'epuration correspondant - Google Patents

Catalyseur d'epuration de gaz d'echappement et procede d'epuration correspondant Download PDF

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Publication number
WO1997037761A1
WO1997037761A1 PCT/JP1997/001211 JP9701211W WO9737761A1 WO 1997037761 A1 WO1997037761 A1 WO 1997037761A1 JP 9701211 W JP9701211 W JP 9701211W WO 9737761 A1 WO9737761 A1 WO 9737761A1
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Prior art keywords
exhaust gas
catalyst
gas purifying
iridium
sulfur
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PCT/JP1997/001211
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English (en)
Japanese (ja)
Inventor
Akihisa Okumura
Masao Hori
Hideki Gotoh
Makoto Horiuchi
Original Assignee
Ict Co., Ltd.
International Catalyst Technology, Incorporated
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from JP08971696A external-priority patent/JP3956158B2/ja
Priority claimed from JP32051696A external-priority patent/JP3865838B2/ja
Priority claimed from JP32053196A external-priority patent/JP4330666B2/ja
Application filed by Ict Co., Ltd., International Catalyst Technology, Incorporated filed Critical Ict Co., Ltd.
Priority to DE69738063T priority Critical patent/DE69738063T2/de
Priority to US08/973,684 priority patent/US6214307B1/en
Priority to CA002223458A priority patent/CA2223458C/fr
Priority to KR1019970708846A priority patent/KR100300825B1/ko
Priority to EP97916636A priority patent/EP0832688B1/fr
Publication of WO1997037761A1 publication Critical patent/WO1997037761A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/468—Iridium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
    • B01J27/053—Sulfates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1028—Iridium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/204—Alkaline earth metals
    • B01D2255/2042—Barium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/206—Rare earth metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/2073—Manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20738—Iron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20746—Cobalt
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20753—Nickel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/40—Mixed oxides
    • B01D2255/407—Zr-Ce mixed oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/50—Zeolites
    • B01D2255/504—ZSM 5 zeolites
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention reduces hydrocarbons, carbon monoxide and nitrogen oxides, particularly nitrogen oxides, in exhaust gas discharged from internal combustion engines such as gasoline engines, diesel engines, boilers, and industrial blunts.
  • the present invention relates to an exhaust gas purifying catalyst and an exhaust gas purifying method.
  • Hydrocarbons hereinafter referred to as HC
  • carbon monoxide hereinafter referred to as C ⁇
  • nitrogen oxides hereinafter referred to as N
  • HC Hydrocarbons
  • C ⁇ carbon monoxide
  • N nitrogen oxides
  • AF is larger than the stoichiometric ratio, that is, in an atmosphere in which oxygen is excessively present in exhaust gas.
  • oxidizing atmosphere an atmosphere in which oxygen is excessively present in exhaust gas.
  • excess oxygen is present in the exhaust gas in excess of the amount that completely burns unburned components such as HC and CO. Therefore, N ⁇ is reduced by a normal three-way catalyst. It was difficult to remove.
  • the exhaust gas is a gas in an oxidizing atmosphere
  • the exhaust gas from diesel engines which is a fixed generation source for boilers, etc.
  • is a reducing agent such as ammonia, hydrogen or carbon monoxide.
  • a method of removing NO x by using NO is known.
  • this method requires a separate device for adding the reducing agent and a special device for collecting and treating the unreacted reducing agent, which leads to a complicated and large-sized device as a whole. As a result, there is a problem that it is unsuitable for an engine that is a source of movement of vehicles and the like.
  • NO x removal catalysts include, for example, transition metal ion-exchanged aluminum silicates such as copper ions (Japanese Patent Application Laid-Open No. 60-125250, Japanese Patent Application Laid-Open No. No. 1 009 19, U.S. Pat. No. 4,297,328), or a metal-aluminosilicate (JP-A-3-127628) Gazettes, Japanese Patent Application Laid-Open No. 3-229620, and silicon aluminum phosphate (Japanese Patent Application Laid-Open No. 1-128488) have been proposed.
  • Et al is, in a catalyst for NO x removal in the oxidizing atmosphere, Lee Li indium was supported on a refractory inorganic oxide such as alumina catalyst is disclosed (Japanese Patent Publication 5 6 - 5 4 1 7 3 No., Japanese Patent Publication No. 57-133332).
  • Japanese Patent Publication 5 6 - 5 4 1 7 3 No. Japanese Patent Publication No. 57-133332
  • Japanese Patent Publication No. 57-133332 Japanese Patent Publication No. 57-133332
  • the oxygen concentration in the exhaust gas is 3% by volume or less is shown, and the diesel engine containing more oxygen than the exhaust gas is not used. No consideration has been given to N ⁇ X purification performance and durability for engine exhaust gas.
  • the examples in each of the above publications show only the maximum NO x removal rate, and the temperature range showing the maximum NO x removal rate is the light-off characteristic. Are not specified except where indicated.
  • the light-off characteristics indicate exhaust gas purification characteristics at various exhaust gas temperatures.
  • N ⁇ X in exhaust gas is efficiently decomposed and removed, and furthermore, it has excellent high-temperature heat resistance, and exhibits catalytic activity over a wide temperature range.
  • N_ ⁇ x removing catalyst is at present or not been developed.
  • N ⁇ x is contained in exhaust gas at the same time.
  • disadvantage N_ ⁇ x purifying ability is lowered due connection over time for adsorption of the sulfur oxides.
  • An object of the present invention is to provide an exhaust gas purifying catalyst and an exhaust gas purifying method exhibiting an activity in the above.
  • a catalyst has been proposed in which an iridium composite oxide is supported together with a noble metal such as platinum, rhodium, and palladium (Japanese Patent Application Laid-Open No. 5-27739). Although this method can improve the heat resistance of the catalyst, the N ⁇ x removal ability in the high temperature range is lower in the operating temperature range than in other temperature ranges.
  • the present invention has been made in view of the above-mentioned conventional problems, and its object is to
  • An object of the present invention is to provide an exhaust gas purifying catalyst and an exhaust gas purification method that can suppress a transition of a developing temperature to a high temperature side. Disclosure of the invention
  • the present inventors have conducted intensive studies to solve the above problems, and as a result, have found that a catalyst containing iridium and sulfur is effective in solving the above problems. Was completed.
  • N_ ⁇ x removal catalyst as an exhaust gas purifying catalyst of the present invention, in order to solve the above problems, as a catalytically active substance, and the Toku ⁇ that you and a Yi Li indium and sulfur.
  • the iridium is preferably supported on a substrate containing sulfur.
  • the sulfur is desirably in the form of a sulfate group.
  • the NOx removal catalyst can remove NOx under an oxidizing atmosphere by having iridium as a catalytically active substance, and can further reduce the NOx catalyst by having sulfur. Its activity can be improved, it shows activity over a wide temperature range in removing NOx in an oxidizing atmosphere, and it has excellent heat resistance and durability.
  • the NOx removal catalyst contains iridium and sulfur as a catalytically active substance for removing NC, is supported on the above-mentioned base material containing iridium or sulfur, and contains the above-mentioned sulfur. In the form of sulfates.
  • a base compound containing a sulfate group such as sulfur-bearing sulfate-bearing aluminum or sulfur-containing sulfuric acid, or a base compound containing the above-mentioned base material is usually used as a catalyst-supporting material.
  • a refractory inorganic oxide used as a carrier for example, Hi-Alumina, or a mixture with active alumina such as 7, ⁇ , ⁇ , 0, etc .; Mixtures (including mixed sinters) of the composite oxide of each of the above refractory inorganic oxides with the above-mentioned base compound, and aluminum phosphate, crystalline aluminum silicate, and silicon alcohol A mixture of minophosphate and the like and the above-mentioned base compound can be used.
  • the content of iridium is preferably 0.5 to 10% by weight with respect to the base material supporting the iridium as a catalyst component. 0. When 5 are weighing less than 96, which decreases or Nyu_ ⁇ ⁇ removal efficiency, it can not be obtained catalytic activity commensurate in supported amount be supported beyond the 1 0% by weight.
  • the iridium source is not particularly limited. For example, a water-soluble iridium salt such as iridium chloride or trichlorohexaneminiridium is preferably used.
  • the method for supporting the solid on the substrate is not particularly limited, and an ordinary supporting method is used.
  • an aqueous solution of an iridium salt is impregnated into a substrate and then dried and fired; (2) an aqueous solution of an iridium salt is introduced into the substrate and mixed. After that, it is reduced by a reducing agent such as hydrazine and supported.
  • the supporting ratio of sulfur to iridium is preferably 1: 5 to 50: 1 by weight. When the loading ratio of sulfur becomes larger than the 50: 1 ratio, the initial activity decreases, and when the loading of sulfur becomes smaller than the 1: 5 ratio, the activation temperature range becomes narrow.
  • the sulfur source for example, sulfuric acid, sulfate, sulfite, sulfide and the like are used.
  • the sulfur can be added by (1) a method of adding sulfuric acid to a substrate, followed by drying and calcining; A method in which a solution of the above-mentioned sulfur-containing compound is immersed in a substrate, and dried and fired. (3) Among sulfates, sulfides, etc., an insoluble or slightly soluble compound is used as the iridium substrate And (4) a method of mixing and using an insoluble or slightly soluble compound of sulfate, sulfide, and the like, and a substrate supporting a solid.
  • the specific use of the exhaust gas purifying catalyst is described as follows: (1) A method in which the catalyst itself is formed into a predetermined shape, for example, a spherical shape or a cylindrical shape,
  • a catalyst component is coated and supported on a carrier called a three-dimensional structure.
  • the three-dimensional structure include a honeycomb monolithic carrier, a foam-shaped carrier, a corrugated-shaped carrier, and the like, and the material is preferably made of ceramic or metal.
  • integral structure When using a body structure or an inert inorganic carrier (hereinafter referred to as “integral structure”),
  • the catalyst-carrying substrate is wet-pulverized with a ball mill or the like to form an aqueous slurry, and the integrated structure is dipped, dried and fired.
  • the integrated structure or the like coated with the catalyst support is immersed in an iridium-containing aqueous solution, dried and fired, and further immersed in a sulfur-containing solution, dried and fired.
  • (C) Iridium is pre-supported on a base material, and is further made into an aqueous slurry by means of a ball mill or the like.
  • the support base material is impregnated with a sulfur-containing solution, and the powder obtained by firing is converted into an aqueous slurry using a ball mill or the like, and the integrated structure is immersed in the aqueous slurry to support the sulfur.
  • Iridium is preliminarily supported on a substrate, and a compound containing sulfur is mixed to form an aqueous slurry using a ball mill or the like, and the integrated structure is immersed in the aqueous slurry and dried. And firing method. Among these methods, each of the methods (2) (a) to (g) is preferable.
  • the coating amount of the catalyst component is 50 to 40 Og per liter of the integral structure or the like. If the amount is less than 500 g, the catalytic activity is reduced. If the amount exceeds 400 g, the catalytic activity corresponding to the supported amount cannot be obtained.
  • the present inventors have found that excellent oxidation activity HC :, CO, not a reducing atmosphere but also reduces rather by efficiently NO x in an oxidizing atmosphere, and heat resistance, excellent durability, and et a wide temperature range
  • HC oxidation activity
  • the present inventors have made intensive studies.
  • the present inventors have developed a refractory inorganic compound carrying at least one element selected from the group consisting of platinum, palladium and rhodium, and a sulfur-containing compound carrying iridium.
  • the inventors have found that a catalyst having a metal sulfate is effective in solving the above-mentioned problems, and have completed the present invention.
  • the exhaust gas purifying catalyst includes a refractory inorganic compound selected from the group consisting of platinum, palladium and rhodium, and a refractory inorganic compound entrusted with at least one kind of element. And metal sulfates carrying the same.
  • HC and CO are reduced by oxidation to purify exhaust gas, and a reducing atmosphere, and Even when the exhaust gas is in an oxidizing atmosphere in a relatively low temperature range, the function of reducing ⁇ ⁇ ⁇ ⁇ ⁇ from the exhaust gas and the action of the iridium supported on the metal sulfate cause the sulfur oxides contained in the exhaust gas while suppressing a decrease in catalytic activity, is relatively high temperature region at or one oxidizing atmosphere, it is to have the combined function of reducing New Omicron chi in the presence of HC from the exhaust gas.
  • a lower layer of a refractory inorganic compound carrying at least one element selected from the group consisting of platinum, palladium and rhodium among the catalyst components of the exhaust gas purifying catalyst is used.
  • a metal sulfate having an upper layer carrying an indium may be arranged so as to face the flow of the exhaust gas.
  • the number of the layers may be any number as long as it is two or more layers, and the number can be appropriately changed for the convenience of preparing the catalyst.
  • the respective catalyst components are arranged in the upper layer and the lower layer, respectively, the respective catalyst components are separated from each other, so that the metal sulfate carrying the silica arranged in the upper layer has
  • the exhaust gas purification function that reduces ⁇ ⁇ ⁇ in the presence of HC and the HC oxidation reaction of the refractory inorganic compound carrying the above element disposed in the lower layer are prevented from competing with each other. Is stopped.
  • the exhaust gas purifying catalyst has a catalyst composition of the exhaust gas purifying catalyst, a metal sulfate carrying iridium in front of the exhaust gas, and a platinum, palladium and rhodium in the rear.
  • a refractory inorganic compound carrying at least one selected element hereinafter referred to as a platinum element may be arranged.
  • the exhaust gas purifying catalyst is divided into a plurality of solids, and the solid at the preceding stage contains metal sulfate carrying a solid with respect to the flow of exhaust gas.
  • An object may be arranged, and an individual containing a refractory inorganic compound carrying a platinum group element may be arranged in the latter stage.
  • the metal sulfate and the refractory inorganic compound are separate from each other. Therefore, as described above, each of the purification functions by the platinum-based element is reduced by the competition described above. Therefore, it is possible to provide an exhaust gas purifying catalyst that can maximize each of the above purifying functions.
  • the solid at the former stage include, for example, a catalyst body formed of only metal sulfate supporting iridium, or having a characteristic shape formed by adding other components such as an activation aid and a molding aid.
  • the catalyst may be any one of catalysts in which a carrier such as a three-dimensional structure supports a metal sulfate that supports iridium.
  • Examples of the latter individual include, for example, only a refractory inorganic compound carrying at least one element selected from the group consisting of platinum, palladium and rhodium, and Either a catalyst body formed into a characteristic shape by adding other components such as a molding aid, or a catalyst body in which a carrier containing a refractory inorganic compound described above is supported on a carrier such as a three-dimensional structure. You can No.
  • the metal sulfate supporting iridium is desirably an alkali earth metal sulfate.
  • the alkaline earth metal sulfates purification function of reducing Nyu_ ⁇ ⁇ Lee Li indium is promoted is the al and is a child exhibits catalytic activity in a wide temperature range of the exhaust gas It is possible.
  • the iridium-supported metal sulfate is further supported by a compound of at least one element selected from the group consisting of tin, gallium, germanium, and gaynium. Thereby, higher NO purification activity can be obtained.
  • an exhaust gas purifying catalyst can be used to reduce the exhaust gas purifying catalyst.
  • the exhaust gas temperature at the catalyst inlet in the used catalyst bed can be set to a wider temperature range up to a lower temperature range, such as 200 to 700 ° C. It becomes possible.
  • Exhaust gas purifying catalyst as a catalytically active material for removing N_ ⁇ x, has a refractory inorganic compound carrying a platinum-based element, and a gold ⁇ salt carrying Lee Li indium .
  • the refractory inorganic compound As the refractory inorganic compound, the above-mentioned base material can be used. In order to improve the thermal stability of these refractory inorganic oxides, rare earth metals such as lanthanum, cerium, and yttrium, and alkali metals such as magnesium, calcium, and zinc are used. Lithium earth metals and their oxides Compounds can be added to the refractory inorganic oxide.
  • the content of the platinum-based element is preferably 0.1 to 20% by weight with respect to the catalyst-carrying support.
  • the platinum-based element source is not particularly limited, but water-soluble salts such as chloroplatinic acid, rhodium nitrate, and palladium nitrate are preferably used.
  • the method of supporting the platinum-based element on the refractory inorganic compound is not particularly limited, and a normal supporting method is used. For example, (1) a method in which an aqueous solution of a salt of a platinum-based element is impregnated with a refractory inorganic compound and then dried and fired; (2) an aqueous solution of a salt of a platinum-based element is mixed with the refractory inorganic compound. And a method in which the platinum-based element is supported on a refractory inorganic compound by reducing with a reducing agent such as hydrazine or the like.
  • a reducing agent such as hydrazine or the like.
  • metal sulfates supporting silica examples include alkaline earth metal sulfates such as magnesium sulfate, calcium sulfate, sodium tin sulfate, and barium sulfate, titanyl sulfate, zirconium sulfate, aluminum sulfate, and the like. Transition metal sulfates such as light gold sulfate, manganese sulfate, cobalt sulfate, and iron sulfate can be used. Of these, alkaline earth metal sulfates are preferred, and more preferably, barium sulfate is used.
  • the iridium content is based on the metal sulfate carrying iridium.
  • iridium source for example, iridium chloride, tricyclohexylamine, etc.
  • a water-soluble iridium salt such as sodium iridium is preferably used.
  • the method for supporting the metal on the metal sulfate is not particularly limited, and a conventional supporting method is used. For example, (1) impregnating the metal sulfate with an aqueous solution of an iridium salt, and drying and firing (2) After mixing an aqueous solution of an iridium salt and a metal sulfate, the iridium obtained by reducing the above iridium salt with a reducing agent such as hydrazine is converted into a metal sulfate. For example, there is a method of carrying the compound.
  • the metal sulfate may further carry a compound of at least one element selected from the group consisting of tin, gallium, germanium, and gayne. .
  • the compound is not particularly limited, but preferably includes an oxide of the above element. It is also possible to add these elements in the form of a chloride or the like and then form the oxide by firing.
  • the amount of the above element added to the metal sulfate is preferably about 0.01 to 10 times the weight of iridium. When the amount is less than 0.01, the effect of the addition is not observed, and even when the amount is more than 10 times, the catalytic activity cannot be obtained in a manner commensurate with the supported amount.
  • the method for supporting the above element on the metal sulfate is not particularly limited, and a usual supporting method is used. For example, (1) a method of mixing with iridium-supported metal sulfate, (2) a A method in which iridium is supported simultaneously with metal sulfate, (3) a method in which an oxide of the above element is mixed with metal sulfate to support iridium, and (4) a metal sulfate in which iridium is supported. On the other hand, it is possible to use a method of infiltrating a solution of a soluble compound of the above element, followed by drying and firing. The specific mode of using the above catalyst is the same as described above. You.
  • the coating amount of the catalyst component depends on the amount of the refractory inorganic compound supporting the platinum element and the metal sulfate supporting the iridium.
  • each liter is 10 to 400 g. If the amount is less than 100 g, the catalytic activity is reduced. If the amount is more than 400 g, the activity corresponding to the supported amount cannot be obtained.
  • the inventors of the present invention efficiently decompose and remove NOx in exhaust gas even in an oxidizing atmosphere, have excellent heat resistance and durability in a high temperature range, exhibit catalytic activity in a wide temperature range, and have low catalytic activity.
  • the present inventors have found that a catalyst containing at least one element selected from the group consisting of iridium, sulfur, calcium, strontium, and lithium solves the above problem.
  • the present inventors have found that the present invention is effective, and have completed the present invention.
  • N_ ⁇ x removal removed by catalyst of still another exhaust gas purifying catalyst of the present invention in order to solve the above problems, and Lee Li indium, and sulfur, force Rushiumu, scan collected by filtration Nchiumu, Li It is characterized in that it contains at least one element selected from the group consisting of elements as a catalytically active substance.
  • the catalytic activity of the iridium for removing the oxygen can be improved over a wide temperature range.
  • iridium and sulfur are By coexisting with elemental group elements, diffusion of iridium generated at high temperatures can be suppressed, and the heat resistance and durability of the catalyst can be improved, especially in the high temperature range. .
  • the iridium forms a composite oxide with the element.
  • the iridium composite oxide is preferably supported on a substrate containing sulfur.
  • the sulfur is preferably in the form of a sulfate group.
  • the catalyst since it has a structure in which iridium or a compound oxide is formed with an element of the above element group, diffusion of iridium can be prevented, and the catalytic activity can be improved. And improve the ripening resistance and durability.
  • the catalyst by supporting the iridium composite oxide on a substrate containing sulfur, the catalyst exhibits catalytic activity in a wider temperature range and has excellent durability in a wide temperature range. Can be.
  • the sulfur in the form of a sulfate group, the sulfur can be further stably supported, the excellent catalytic activity can be stabilized, and the durability can be further improved.
  • the N ⁇ x removal catalyst uses expensive materials such as metal carbides such as silicon carbide (SiC) and metal nitrides such as gay nitride (SiN). Cost can be reduced.
  • O x removing catalyst is a catalytically active material for removing NO x, and a y re indium and sulfur.
  • This iridium is at least one of the elements selected from the group consisting of calcium, strontium, and barium. Used as a compound oxide formed with an element.
  • the sulfur is contained in a substrate that holds the catalytically active substance on the surface in the form of sulfate.
  • the iridium composite oxide is supported on the base material containing sulfur.
  • a refractory inorganic compound carrying a sulfur root or a compound containing sulfur such as a sulfate such as barium sulfate, a sulfite or a sulfide can be used alone.
  • a refractory inorganic compound those described above can be used.
  • the base material may be a mixed sintered body obtained by mixing the refractory inorganic compound and the base material compound and then sintering the mixture.
  • the content of iridium to be supported is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, based on the base material. New When the iridium content is less than 0.1% by weight, the NO x removal rate decreases. On the other hand, if the iridium content exceeds 20% by weight, it is not possible to obtain a catalytic activity commensurate with the supported amount.
  • the above may include the aforementioned refractory inorganic compound.
  • the refractory inorganic compound may be in a state of being complexed with another catalyst component.
  • the strength of the catalyst can be improved.
  • the source of iridium is not particularly limited.
  • a water-soluble iridium salt such as iridium chloride—a trichloride hexamine iridium salt. It is preferable to use.
  • the raw materials for carnum, strontium, and barium are not particularly limited, and for example, nitrates, acetates, chlorides, sulfates, oxides, peroxides, hydroxides, and the like may be used. Can be.
  • the loading ratio of one or more elements (hereinafter referred to as component H) to the solid is 1: 5 to 200: 1 in molar ratio. Is preferred. 2 0 0: the loading ratio of component H is much larger than the 1 ratio, NO x removal rate decreases. On the other hand, when the loading ratio of the component H is smaller than the ratio of 1: 5, heat resistance and durability in a high temperature range are reduced.
  • the method for supporting the composite oxide of the solid on the substrate is not particularly limited, and the above-described ordinary supporting method is used.
  • the supporting ratio of sulfur to iridium is preferably 1: 5 to 50: 1 by weight. If the supported ratio of sulfur is higher than the 50: 1 ratio, the initial catalytic activity decreases, whereas if the supported ratio of sulfur is lower than the 1: 5 ratio, the catalytic activity decreases.
  • the effective temperature range narrows.
  • the source of sulfur is not particularly limited, and for example, the above-mentioned sulfuric acid, sulfate, sulfite, sulfide and the like are used.
  • the sulfur can be added by (1) a method of adding sulfur to a refractory inorganic compound, followed by drying and baking, and (2) a sulfur or sulfite, etc., which are soluble in organic solvents and sulfur or water-soluble.
  • the solution of the above sulfur-containing compound is immersed in a refractory inorganic compound using the containing compound.
  • a method in which an insoluble or slightly soluble compound is mixed with a substrate supporting iridium and the like are used.
  • the specific aspect of the exhaust gas purifying catalyst is the same as described above.
  • the coating amount of the catalyst component is also the same as described above.
  • the present inventors have shown the activity of efficiently removing NX in not only a reducing atmosphere but also an oxidizing atmosphere and exhibiting an activity of removing NC in a wide temperature range, and have excellent heat resistance and durability.
  • the present inventors have conducted intensive studies. As a result, they have found that a catalyst containing iridium, a rare earth element, and sulfur is effective in solving the above-mentioned problems, and have completed the present invention. That is, the inventors of the present invention are characterized in that the exhaust gas purifying catalyst contains iridium, a rare earth element, and sulfur.
  • the synergistic action of iridium and sulfur exerts a performance of efficiently purifying NOx in the presence of HC even in an oxidizing atmosphere.
  • high performance is maintained even when used under practical use conditions for a long time, and the temperature at which NO x purification performance is exhibited is suppressed from shifting to higher temperatures. be able to. This makes it possible to use it for a long time without changing the reaction conditions.
  • the exhaust gas purifying catalyst described above eliminates expensive metal carbides and metal nitrides as compared with conventional catalysts in which metal carbide or metal nitride supports dia- lytes and rare earth elements. Not only can sulfur be contained using inexpensive metal sulphates, etc., but it is possible to reduce costs compared to the conventional catalysts described above.
  • sulfur is contained as a metal sulfate, and it is more desirable that sulfur be contained as a sulfate of an alkaline earth metal.
  • the function of purifying iridium's N C is promoted, and the activity can be exhibited in a wide temperature range.
  • the rare earth elements are cerium (Ce), lanthanum (La), yttrium (Y), neodymium (Nd), and praseodymium (P It is desirable that it be contained as an oxide containing at least one element selected from the group consisting of r)).
  • the rare earth element is at least one element selected from the group consisting of cerium, lanthanum, yttrium, neodymium, and praseodymium, and More preferably, it is contained as a composite oxide containing at least one element selected from the group consisting of manganese, iron, cobalt, nickel, copper, and zinc.
  • the exhaust gas purifying catalyst contains a compound of at least one element selected from the group consisting of tin, gallium, germanium, and gayne. As a result, the purification performance can be further improved.
  • the above exhaust gas purifying catalyst is It is desirable to include as many refractory inorganic compounds as possible. Thereby, the strength can be improved.
  • the exhaust gas purifying catalyst as a catalytically active component for removing NO x, and includes a Lee Li indium, and rare earth elements, and sulfur.
  • rare earth element j is scandium (S c), yttrium, and lanthanide.
  • the exhaust gas purifying catalyst may further contain a refractory inorganic compound in addition to iridium, a rare earth element, and sulfur.
  • a refractory inorganic compound the refractory inorganic oxide described above can be used.
  • the refractory inorganic compound may be present in a state of being compounded with the rare earth element, for example, as a composite oxide with the rare earth element.
  • sulfur for example, sulfuric acid, sulfate, sulfite, sulfide and the like are used, and it is preferable that the sulfur is contained as a compound having a sulfate group.
  • the compound having a sulfate group include sulfate group-supported aluminum, metal sulfate, a mixture of a metal sulfate and a catalyst-carrying substrate (including a mixed sintered body) or a carrier. Can be used.
  • the above-mentioned metal sulfate the above-mentioned alkaline earth metal sulfate, the above-mentioned nonmetal sulfate, and the above-mentioned transition gold sulfate can be used.
  • alkaline earth metal sulfates are preferred, and more preferably, barium sulfate is used.
  • the catalyst-supporting substrate used as a metal sulfate carrier may be any refractory inorganic compound, and the above-described refractory inorganic oxide generally used as a catalyst-supporting carrier is used. be able to.
  • the method for supporting the metal sulfate on the catalyst-supporting substrate is as follows: (1) a method in which sulfuric acid is added to the catalyst-supporting substrate, followed by drying and firing; and (2) an organic method. A method of immersing a solvent-soluble and / or water-soluble metal sulphate solution in a catalyst-carrying substrate, followed by drying and calcining may be used.
  • metal sulfates that are insoluble in water for example, barium sulfate, etc.
  • the content of the solid is preferably from 0.1 to 20% by weight, more preferably from 0.5 to 10% by weight, based on the substrate supporting the solid as a catalyst component. Is even more preferred. If the amount is less than 0.1% by weight, the efficiency of removing N 2 O decreases, and even if the amount exceeds 20% by weight, no catalytic activity corresponding to the content is obtained.
  • the iridium source is not particularly limited, but for example, a water-soluble iridium salt such as iridium chloride or trichloro-hexaammonium iridium is preferably used.
  • the weight ratio of sulfur to silica is preferably 1: 5 to 50: 1.
  • the presence state of iridium in the exhaust gas purifying catalyst is not particularly limited, and may be any state in which iridium coexists with sulfur. However, it is preferable that iridium is supported on a sulfur-containing compound. As the compound to be contained, a compound having a sulfate group is desirable.
  • iridium is supported on a catalyst supporting substrate together with a sulfur-containing compound. It may be.
  • a method of supporting the iridium on the sulfur-containing compound
  • a sulfur-containing compound such as an insoluble or slightly soluble sulfate or sulfide is used, and the catalyst is loaded on the solution of the sulfur-containing compound. Soak the substrate
  • Drying and calcining methods a method in which a sulfur-containing compound such as an insoluble or slightly soluble sulfate or sulfide is mixed with a catalyst-carrying substrate carrying an iridium can be used.
  • the rare earth element is an oxide containing at least one or more elements selected from the group consisting of cerium, lanthanum, yttrium, neodymium, and praseodymium (hereinafter, referred to as rare earth oxide). It is more desirable that they are contained as a complex oxide containing these elements.
  • the rare earth element is contained as a composite oxide containing at least two or more elements selected from the group consisting of cerium, lanthanum, yttrium, neodymium, and praseodymium. It is particularly desirable to be there.
  • the rare earth element may include at least one element selected from the group consisting of cerium, lanthanum, yttrium, neodymium, and praseodymium, and titanium, manganese, iron, cobalt, and the like. It is particularly desirable that it be contained as a composite oxide containing at least one element selected from the group consisting of, nickel, copper, and zinc.
  • oxides of each element or precursors of these oxides for example, nitrates, acetates, chlorides, sulfates, oxalates, etc. of each element, followed by firing;
  • a treatment for forming a coprecipitate or a mixed sol-gel is performed.
  • i) and h) are particularly desirable.
  • the amount of the rare earth element added is calculated as oxides and 1 g of iridium.
  • the amount of rare earth element added is 0.
  • the amount is less than 1 g, a sufficient effect cannot be obtained, and if the amount of the rare earth element is 500 g or more, no effect commensurate with the amount is found.
  • the state of the rare earth element in the exhaust gas purifying catalyst is not particularly limited, but it is particularly desirable that the rare earth element be supported on a sulfur-containing compound together with iridium.
  • the method for supporting the rare earth element together with the solid on the sulfur-containing compound is not particularly limited, and a common supporting method is used.
  • a sulfur-containing compound supporting the solid and a rare earth oxide may be used.
  • a method in which a rare earth oxide is supported on a sulfur-containing compound simultaneously with iridium (3) a method in which iridium is supported on a mixture obtained by mixing the rare earth oxide with a sulfur-containing compound; 4)
  • a method of infiltrating a solution of a soluble compound of a rare earth element into a sulfur-containing compound supporting an iridium, followed by drying and firing can be used.
  • the exhaust gas purifying catalysts described above include, in addition to iridium, sulfur, and rare earth elements, tin, gallium, germanium, and silicon as catalytically active components for removing NOx. It is desirable to include a compound of at least one element selected from the group consisting of: The compound is not particularly limited, but an oxide of the above element is preferable. In addition to the method of adding an oxide of the above element, the above compound can be made into the form of an oxide by a method of adding these elements in the form of a chloride or the like and then firing. .
  • the amount of addition of the compound of at least one element selected from the group consisting of tin compounds, gallium, germanium, and gayne is 0.1 g to 500 g with respect to iridium lg. Desirable. If the amount is less than 0.1 g, a sufficient effect cannot be obtained. If the amount exceeds 500 g, an effect corresponding to the added amount cannot be obtained.
  • the specific embodiment of the catalyst is the same as described above.o
  • any one of the above exhaust gas purifying catalysts is used, and the gas space velocity of the exhaust gas passing through the exhaust gas purifying catalyst is 50,000 to 200. It is preferable to set within the range of 0, 00 00 hr 1 . 5, 0 0 0 when it is less than hr is uneconomical Narisuki catalyst volume or rather large, 2 0 0 0 0 0 When exceeding hr 1 is the NO x purification rate is low Down.
  • the exhaust gas temperature in the above purification method is in the range from 200 ° C. to 700, more preferably from 250 to 600 e C at the catalyst inlet. If it is less than 2 0 0 ° C N_ ⁇ x cleansing ability is significantly deteriorated, when more than 7 0 0 ° C NO x purification rate also decreases.
  • the catalyst for the exhaust gas purification in particular, in the removal of N_ ⁇ x under oxidizing ⁇ gas, the temperature of the exhaust gas is effective from the time of low temperature, the activity in a wide temperature range
  • the exhaust gas purification catalyst used has excellent heat resistance and durability, the exhaust gas becomes an oxidizing atmosphere, and the exhaust gas has a wide temperature fluctuation range. It is suitably used for reducing the exhaust gas of internal combustion engines such as lean-burn engines.
  • the exhaust gas may be exhaust gas exhausted from internal combustion engines such as gasoline engines, diesel engines, boilers, industrial plants, etc. used as automobile engines, etc., and its composition is limited. It is not something that is done. BRIEF DESCRIPTION OF THE FIGURES
  • FIG. 1 shows the N ⁇ x light-off performance of the completed catalyst (1) described in Example 1 relating to the exhaust gas purifying catalyst of the present invention with respect to the model exhaust gas (oxidizing atmosphere) at the initial stage and after the endurance test. It is the graph respectively shown.
  • FIG. 2 shows the 1 ⁇ '0X light-off performance of the completed catalyst (5) described in Example 5 relating to the exhaust gas purifying catalyst of the present invention with respect to the model exhaust gas at the initial stage and after the durability test. It is a graph shown.
  • Figure 3 shows the above model exhaust gas for the comparative catalyst (A) of Comparative Example 1. These graphs respectively show the N ⁇ x light-off performance at the initial stage and after the durability test.
  • FIG. 5 shows the NC light-off performance of the completed catalyst (10) described in Example 10 according to the exhaust gas purifying catalyst of the present invention with respect to the model exhaust gas at the initial stage and after the durability test, respectively. It is a graph.
  • FIG. 7 is a graph showing the NOx light-off performance of the comparative catalyst (B) of Comparative Example 2 at the initial stage and after the durability test with respect to the model exhaust gas.
  • FIG. 8 shows the NOx light-off performance of the completed catalyst (17) described in Example 17 according to the exhaust gas purifying catalyst of the present invention at the initial stage and after the durability test with respect to the model exhaust gas. It is a graph. BEST MODE FOR CARRYING OUT THE INVENTION
  • a powder catalyst composed of the active Arumi Na having dispersed in, and wet Kona ⁇ obtain an aqueous slide Li one of the catalyst powder by a ball mill, followed by to the aqueous Sula rie, co Monolithic honeycomb carrier (manufactured by Nippon Glass Co., Ltd., having 400 gas flow cells per square inch in cross section, diameter 33 mm0, length 76 mmL, volume 6 5 ml), the excess aqueous slurry was blown off the honeycomb carrier with compressed air to remove it.
  • the honeycomb carrier having the aqueous slurry on the inner surface of each cell was dried at 120 ° C. for 2 hours, and then fired at 500 ° C. for 2 hours.
  • the above honeycomb carrier was immersed in an aqueous solution of 1.5 mO1Z liter of sulfuric acid, and excess sulfuric acid was blown off with compressed air, dried at 120 and dried for 2 hours to obtain a completed catalyst (1). Obtained.
  • 100 g of activated alumina, 5 g of iridium, 5 g of sulfur, and 1 g of activated alumina were used for one litre of the honeycomb support. 5% by weight of iridium and 5% by weight of sulfur.
  • Example 3 Prepared in the same manner as in Example 1 above, except that the aqueous solution of sulfuric acid of 0.3 m 0 1 nil was used instead of the aqueous solution of sulfuric acid of 1.5 m 0 1 Z litz in Example 1 above. Thus, a completed catalyst (2) was obtained. In this completed catalyst (2), 100 g of activated alumina, 5 g of iridium, and 1 g of sulfur per 1 liter of honeycomb carrier, that is, 1 g of activated alumina, 5% by weight of rim and 1% by weight of sulfur were carried. (Example 3)
  • a finished catalyst (3) was obtained in the same manner as in Example 1 except that the aqueous sulfuric acid solution of 6 m 01 Z lit.
  • Example 1 in Example 1 of the. 5 m 0 1 instead of the aqueous solution of sulfuric acid re Potter, except for using an aqueous solution containing sulfuric acid mosquitoes Li um [K 2 S 0 4] 2 7. 2 g, the Example 1
  • the finished catalyst (4) was prepared in the same manner as described above.
  • 100 g of activated aluminum, 5 g of iridium, and 5 g of sulfur per 1 liter of the honeycomb carrier, that is, activated aluminum as a base material 5% by weight of iridium and 5% by weight of sulfur were supported.
  • Example 6 instead of 100 g of activated alumina in Example 1 described above, barium sulfate! : B a S 0 4] using a 1 0 0 g, except for omitting the Hita ⁇ to aqueous sulfuric acid, producing a complete catalyst (5) was prepared in the same manner as in Example 1. In this finished catalyst (5), 100 g of barium sulfate and 5 g of iridium per 1 liter of honeycomb carrier, that is, iridium was used for 5% by weight was carried, and 7.3% by weight of sulfur was contained. (Example 6)
  • a finished catalyst was prepared in the same manner as in Example 5 except that 5 g of tin oxide (SnO 2 ) was added when preparing the aqueous slurry.
  • Example 7 Except adding oxidation gully um of 5 g in place of tin oxide (Ga 2 0 3) In the above Example 7 was prepared in the same manner as in Example 7, to obtain a complete catalyst (8). In the completed catalyst (8), 5% by weight of gallium oxide was further supported on barium sulfate as the base material.
  • Example 7 in place of the tin oxide, except adding 5 g of germanium oxide and (GeO 2) was prepared as in Example 7, to obtain a complete catalyst (9). In the completed catalyst (9), 5% by weight of germanium oxide was further supported on the barium sulfate as the base material.
  • Example 10 To chloride I Li Jiu ⁇ solution in Example 1 above, except that addition of chloride barium aqueous solution containing the al in Beauty um chloride (B a C 1 2 ⁇ 2 H 2 0 ] 6. 4 g, wherein A completed catalyst (10) was obtained in the same manner as in Example 1. In this completed catalyst (10), 100 g of activated alumina, 100 g of iridium and 1 liter of the honeycomb carrier were used. 5 g, 3.6 g of barium, 5 g of sulfur, that is, 5% by weight of iridium, 3.6% by weight of barium, and 5% by weight of sulfur based on activated alumina as a base material It had been.
  • Example 1 Example 1 was repeated except that the aqueous solution of sulfuric acid of 0.3 m 0 1 liter was used in place of the aqueous solution of 1.5 m 0 / liter of sulfuric acid in Example 10 described above.
  • the finished catalyst (11) was prepared in the same manner as in Example 1. In the completed catalyst (11), 5% by weight of iridium, 3.6% by weight of iridium, and 1% by weight of sulfur were supported on the active alumina as a base material.
  • Example 10 instead of the aqueous solution of iridium chloride containing 5 g of iridium, the aqueous solution of barium chloride containing 6.4 g of barium chloride, and the aqueous solution of 1.5 mo 1 / liter of sulfuric acid in Example 10 described above. Except that an aqueous solution of iridium chloride containing 1 g of iridium, an aqueous solution of barium chloride containing 1.3 g of barium chloride, and an aqueous sulfuric acid solution of 6 mO. was prepared in the same manner as in Example 10 to obtain a completed catalyst (12). In this completed catalyst (12), 1% by weight of iridium, 0.7% by weight of barium, and 20% by weight of sulfur were stored in the active alumina as a base material.
  • Example 14 a completed catalyst (13) was obtained in the same manner as in Example 10 except that an aqueous solution containing 27.2 g of sulfuric acid [K 2 S ⁇ ] was used.
  • aqueous solution containing 27.2 g of sulfuric acid [K 2 S ⁇ ] was used in the completed catalyst (13).
  • 5% by weight of iridium, 3.6% by weight of barium, and 5% by weight of sulfur were supported on active alumina as a base material.
  • Example 1 0 instead of the active alumina 1 0 0 g in Example 1 0 above, with sulfuric acid burr ⁇ [B a S_ ⁇ 4] 1 0 0 g, except for omitting the Hitatagi to aqueous sulfuric acid, the above described The same procedure as in Example 10 was carried out to obtain a finished catalyst (14). In this completed catalyst (14), 5% by weight of iridium was supported on barium sulfate as a base material, and 13.7% by weight of sulfur was contained.
  • Example 10 In the above-mentioned Example 10, except that when the aqueous slurry was obtained, 36.4 g of barium sulfate (BaS04) was added and immersion in the aqueous sulfuric acid solution was omitted. Similarly, a finished catalyst (15) was obtained. In this completed catalyst (15), 3.7% by weight of iridium and 3.7% by weight of sulfur were contained with respect to activated alumina and barium sulfate as tomb materials.
  • BaS04 barium sulfate
  • Example 17 In the same manner as in Example 10 except that an aqueous solution of calcium chloride containing 3.8 g of calcium chloride [CaC122H2 2 ] was used instead of barium chloride in Example I0 described above. It was prepared to obtain a completed catalyst (16). In the completed catalyst (16), 5% by weight of iridium and 1% by weight of carnium were supported on barium sulfate as a base material, and 5% by weight of sulfur was contained. (Example 17)
  • Example 5 the preparation was carried out in the same manner as in Example 5 except that 20 g of the above-mentioned cerium-zirconium composite oxide was added during the preparation of the aqueous slurry, whereby a completed catalyst (17) was obtained.
  • this completed catalyst (17) 100 g of barium sulfate, 5 g of iridium, and cerium-zirconium composite oxide (zirconium: cerium) per liter of honeycomb carrier (4: 1 molar ratio) 20 g was supported.
  • Example 7 A catalyst was prepared in the same manner as in 7, except that a lanthanum nitrate solution was added in an amount of 1 to 8 moles of lanthanum to zirconium when preparing powder a. (18) was obtained.
  • a catalyst was prepared in the same manner as in Example 18 except that a yttrium nitrate solution was used instead of the lanthanum nitrate solution, to obtain a completed catalyst (19).
  • a catalyst was prepared in the same manner as in Example 18 except that a praseodymium nitrate solution was used instead of the lanthanum nitrate solution, to obtain a completed catalyst (20). (Example 21)
  • a catalyst was prepared in the same manner as in Example i8 except for using a neodymium nitrate solution instead of the lanthanum nitrate solution, to obtain a completed catalyst (20).
  • a mixed aqueous solution is prepared by mixing zirconyl nitrate and cerium nitrate such that the mole ratio of zirconium and cerium is 4: 1. This mixed water solution is neutralized with ammonia to form a coprecipitate. The obtained coprecipitate was dried and calcined in air at 500 ° C. for 2 hours to obtain a cerium-zirconium complex oxide (powder b).
  • a catalyst was prepared in the same manner as in Example 17 except that 20 g of the dressing form b was added instead of the powder a, to obtain a completed catalyst (22).
  • Example 2 Instead of the nitric acid ⁇ liquid other adding nitric cobalt solution by the same procedure the catalyst was prepared to give a finished catalyst (2 4) D
  • Example 23 a nickel nitrate solution was added instead of the iron sulfate solution Others were operated in the same manner to prepare a catalyst to obtain a completed catalyst (25).
  • a catalyst was prepared in the same manner as in Example 23 except that a copper nitrate solution was added instead of the iron nitrate solution, to obtain a completed catalyst (26).
  • a catalyst was prepared in the same manner as in Example 23 except that a zinc nitrate solution was added instead of the iron nitrate solution, to obtain a completed catalyst (27).
  • a catalyst was prepared in the same manner as in Example 13 except that a manganese nitrate solution was added instead of the iron nitrate solution, to obtain a completed catalyst (28).
  • Example 17 a completed catalyst (29) was obtained in the same manner as in Example 17, except that 5 g of tin oxide was added when preparing the aqueous slurry. (Example 30)
  • porous powdered activated alumina having a BET surface area of 100 mz / g as a refractory inorganic compound an aqueous solution of chloroplatinic acid containing 5 g of platinum was added and mixed. After drying at 120 ° C. for 2 hours and forming at 500 ° C. for 2 hours, platinum-supported activated alumina (powder d) was obtained.
  • powdered cerium oxide (powder) having the above-mentioned powder d, powder e, and a BET surface area of 50 m 2 / g were added to a ball mill.
  • An aqueous slurry was obtained by further wet milling.
  • aqueous slurry was coated, dried and calcined on a cordierite honeycomb carrier in the same manner as in Example 1 to obtain a completed catalyst (30).
  • the completed catalyst (30) 100 g of activated alumina, 5 g of platinum, 100 g of barium sulfate, and 5 g of iridium were carried per liter of the honeycomb carrier. I was
  • Example 30 described above the first aqueous slurry obtained by wet-grinding the powder d and the powder ⁇ was applied to a honeycomb carrier in the same manner as in Example 30 described above, and dried and fired. Thereafter, the second aqueous slurry obtained by wet-milling the powder e in Example 30 above was applied to the honeycomb carrier coated with the powders d and ⁇ , and dried and fired. Thus, a completed catalyst (31) was obtained.
  • the second layer having the component structure of the powder e in the outer layer is such that the first catalyst layer having the component structure of the powder d in the inner layer is in contact with the honeycomb carrier as the lower layer.
  • the catalyst layer had a multilayer structure of catalyst components provided as an upper layer so as to face the honeycomb carrier with the first catalyst layer interposed therebetween.
  • a third aqueous slurry obtained by wet-pulverizing the powder f and the powder d ′ described in Example 30 was used to prepare a cordierite honeycomb having a length of 38 mm.
  • a catalyst (32-1) (solid) was obtained by coating and drying and calcining in the same manner as in Example 30 except that a carrier was used. In this catalyst (32-1), 100 g of active alumina and 10 g of platinum were supported on 1 liter of the honeycomb support.
  • Example 4 was repeated except that the fourth aqueous slurry obtained by wet-milling the above-mentioned powder e ′ was a cordierite honeycomb carrier having a length of 38 mm. The same coating, drying, and calcination were performed to obtain a catalyst (32-2) (solid).
  • this catalyst (32-2) 100 g of barrier sulfate and 10 g of iridium were supported per liter of the honeycomb carrier.
  • the catalyst (32-2) is located upstream of the exhaust gas flow and the catalyst (32-1) is located downstream of the exhaust gas flow.
  • a completed catalyst (32) comprising the catalyst (32-1) was obtained.
  • the finished catalyst (32) carries 50 g of activated alumina, 5 g of platinum, 50 g of barium sulfate and 5 g of iridium per liter of the entire honeycomb carrier.
  • Example 33 The same procedure as in Example 32 was carried out except that an aqueous solution of palladium nitrate containing 10 g of palladium was used in place of the aqueous solution of chloroplatinic acid containing 10 g of platinum in Example 32 above. 3 3) was obtained.
  • Example 32 The same procedure as in Example 32 was carried out except that in place of the aqueous solution of chloroplatinic acid containing 10 g of platinum, an aqueous solution of nitric acid dilute containing 10 g of rhodium was used. 3 4) was obtained.
  • Example 32 The same procedure as in Example 32 was repeated, except that the aqueous solution of rhodium nitrate containing 2 g of rhodium was used instead of the aqueous solution of chloroplatinic acid containing 10 g of platinum in Example 32 above. ).
  • a comparative catalyst (A) was prepared in the same manner as in Example 1 except that the immersion in sulfuric acid was omitted.
  • this comparative catalyst (A) 5 g of iridium was supported on 100 g of active alumina as a substrate.
  • a comparative catalyst (B) was prepared in the same manner as in Example 1 except that the immersion in sulfuric acid was omitted in Example 10 described above.
  • this comparative catalyst (B) 5 g of iridium was supported on 100 g of active alumina as a base material. (Comparative Example 3)
  • Example 31 only the first slurry was coated to obtain a comparative catalyst (C).
  • this comparative catalyst (C) 5 g of platinum was supported on 10 g of active alumina as a base material.
  • a copper zeolite catalyst prepared according to the method described in Japanese Patent Application Laid-Open No. 60-125250 was used. This will be described as a conventional example.
  • the zeolite having a copper amine complex was collected by filtration from the mixture, washed sufficiently, and dried at 120 ° C. for 24 hours to obtain a zeolite catalyst powder.
  • the zeolite catalyst powder was wet-pulverized with a ball mill to obtain an aqueous slurry.
  • the conventional catalyst (D) was obtained using the aqueous slurry.
  • 100 g of ZSM-5 type zeolite and 5.6 g of copper were supported per liter of the honeycomb support.
  • catalysts (1) to (35), comparative catalysts (A) to (C), and conventional catalysts (D) prepared in Examples I to 35, Comparative Examples 1 to 3, and the conventional example are described.
  • Carbon dioxide (C 0 2) 1 0% by volume
  • Example 1 Fresh Aged Example 1 (1) 72/375 78/380 Example 2 (2) 66/380 72/390 Example 3 (3) 60/385 70/400 Example 4 (4) 64/390 70/400 Example 5 (5) 68/380 74/375 Example 6 (6) 66/375 70/375
  • Example 7 (7) 66/375 79/385 Example 8 (8) 73/377 78/390 Example 9 (9) 72/380 77/388 Comparative Example 1 A 54/400 58/415 Comparative Example 2 B 50/400 44/415 Comparative example 3 C 60/252 38/280 Conventional example D 78/395 58/415
  • each catalyst was filled 20 times per multi-computer to form each packed catalyst bed. Subsequently, the exhaust gas of a commercially available gasoline-lean burn engine was passed with the air-fuel ratio (A / F) adjusted to 21 and the space velocity (S.V.) 160 000 hr catalyst Aging was performed for 20 hours under the condition of a bed temperature of 700 ° C. Thereafter, the performance of each of the packed catalyst beds was evaluated by the method described in the above-described initial performance evaluation. The results are shown in Table 1.
  • the light-off performance of the completed catalyst (1), (5), the comparative catalyst (A), and the conventional catalyst (D) is shown at the initial (Fresh) and after the durability test (Aged). 1 to 4 show.
  • the results at the initial stage (Fresh) are shown by solid lines, and the results after the endurance test (Aged) are shown by broken lines.
  • the catalysts (I) to (9) of the present invention can remove N 0 in an oxidizing atmosphere compared to the comparative catalyst (A) and the conventional catalyst (D). It can be seen that it can be performed over a wide temperature range from lower temperatures (around 300 ° C). In addition, almost no decrease in the catalytic activity after the aging test (Aged) is observed, indicating that the catalyst has sufficient heat resistance and durability.
  • the exhaust gas purifying catalyst contains both iridium and sulfur, so that only iridium is supported.
  • activity increased in the high temperature, N_ ⁇ x conversion over a wide temperature range has become what can be achieved.
  • the conventional catalyst is a copper ion-exchange Zeorai Bok catalysts known as New Omicron chi catalyst for removing in an oxidizing atmosphere (D), a reduction in ⁇ activity after the durability test showed that.
  • the exhaust gas purifying catalyst showed almost no decrease in activity even after the durability test. Therefore, the exhaust gas purifying catalyst has more sufficient heat resistance and durability than the conventional catalyst (D).
  • the conventional catalyst (D) of the conventional example has a high NOx removal rate at the initial stage, but the NOx removal rate after the durability test is about 5/7 that before the durability test, and the completed catalyst (10)- It is much lower than (16). From this, each of the catalysts (10) to (16) is superior in durability to the above-mentioned conventional catalyst (D), and has the highest NOx removal rate after the durability test. It can be seen that the shift at the indicated temperature is small.
  • the exhaust gas purifying catalyst is excellent at a stable temperature or at an optimum temperature at which the catalytic activity is exhibited. For this reason, the exhaust gas purifying catalyst is excellent in heat resistance and durability, and also excellent in stability against exhaust gas purification.
  • the above exhaust gas purifying catalyst contains both the composite oxide of sulfur and sulfur, and thus has a high yield.
  • the catalyst activity is also enhanced at elevated temperatures, to that removal of N_ ⁇ x in a temperature range not wide can be realized Has become.
  • the conventional catalyst is a copper ion-exchange Zeorai bets catalysts known as a catalyze for NO x removal in an oxidizing atmosphere (D) is marked after the durability test It showed a decrease in catalytic activity.
  • the NO x removing catalyst as the exhaust gas purifying catalyst showed almost no decrease in catalytic activity even after the durability test. Therefore, the exhaust gas purifying catalyst has sufficient heat resistance and durability as compared with the conventional catalyst (D).
  • Figure 8 shows the light-off performance of the completed catalyst (17) at the initial stage (Fresh) and after the durability test (Aged).
  • the completed catalysts (17) to (29) contain iridium, a rare earth element, and sulfur, so that Comparative Example 1 containing only iridium was used.
  • Comparative Example 1 containing only iridium was used.
  • the finished catalysts (17) to (29) showed almost no decrease in NOx purification activity after the durability test compared to the conventional catalyst (D) of the conventional example. However, it can be seen that they have sufficient heat resistance and durability.
  • the completed catalyst (17) contains iridium, a rare-earth element, and sulfur, and thus can be compared with the conventional catalyst (D) of the conventional example. It can be seen that ⁇ removal in an oxidizing atmosphere can be performed over a wide temperature range from lower temperatures.
  • the conventional example of a conventional catalyst (D) is 3 with respect to 0 0 ⁇ ⁇ ⁇ purification rate of ° C (conversion) that approximately 5% and less, the finished catalyst (17), 3 0 0 ° C
  • the NOx removal rate at 15% or more was also excellent, and the NOx removal rate at low temperatures was also excellent.
  • the activity of the completed catalyst (17) at high temperatures is improved, and NOx purification in a wide temperature range can be realized.
  • the finished catalyst (17) showed almost no decrease in activity even after the endurance test. That rising temperature of the NO x purification activity is less than about 2 5 0 e C, transition to the high temperature side of the rising temperature of N_ ⁇ purification activity was suppressed. Therefore, the exhaust gas purifying catalyst has sufficient heat resistance and durability as compared with the conventional catalyst (D) of the conventional example.
  • each of the completed catalysts (30) to (35) has an oxidizing atmosphere compared to each of the comparative catalysts (A) to (C) and the conventional catalyst (D). ⁇ ⁇ ⁇ ⁇ with exhaust gas not only at the initial stage but also after endurance test It can also be seen that it can be removed or reduced.
  • each of the completed catalysts (30) to (35) has resistance to poisoning caused by sulfur oxides and the like in exhaust gas, and can exhibit excellent durability. It has become.
  • a model exhaust gas having the following reaction gas composition Y was introduced at a space velocity of 50,000 Ohr- 1 and the catalyst inlet temperature of each catalyst was continuously increased from 150 to 500 ° C. By raising the temperature, the purification rates of N 0 X, HC :, and CO were measured, and the performance of each catalyst at each exhaust gas temperature was evaluated.
  • This reaction gas composition Y is an example assuming the exhaust gas of a gasoline engine having a stoichiometric ratio such as an air-fuel ratio of 14.6, and the exhaust gas composition used is not particularly limited to the above. Not something.
  • Carbon dioxide (C_ ⁇ 2) 1 3% by volume
  • Nitrogen (N z ) balance Table 5 shows the results at the initial stage (Fresh) of the catalysts at the catalyst inlet temperature of 250 ° C and 400 ° C, respectively.
  • the completed catalysts (30) to (35) contain elements such as platinum, so the completed catalyst (5), each of the comparative catalysts (A) to (B), and the conventional catalysts Compared to the catalyst (D), if the air fuel, which is more difficult to purify HC and C0 than the oxidizing atmosphere exhaust gas (reactive gas composition X), burns at a stoichiometric ratio HC, C ⁇ and NO x can be removed or reduced from the combined exhaust gas (reactive gas composition Y) over a wide temperature range from a lower (around 200) exhaust gas temperature.
  • the air fuel which is more difficult to purify HC and C0 than the oxidizing atmosphere exhaust gas (reactive gas composition X)
  • burns at a stoichiometric ratio HC, C ⁇ and NO x can be removed or reduced from the combined exhaust gas (reactive gas composition Y) over a wide temperature range from a lower (around 200) exhaust gas temperature.
  • the exhaust gas purifying catalyst of the present invention eliminates expensive metal carbides and metal nitrides, and is inexpensive as compared with conventional catalysts in which metal is supported on metal carbides or gold nitrides.
  • the use of a compound having an excellent sulfate group has the same activity as that of the conventional catalyst for removing ⁇ ⁇ ⁇ , so that the cost can be reduced compared with the conventional catalyst.
  • JP-7 - sulfuric carrying substrate such S_ ⁇ 4 / Z r 0 2 as a carrier 8 0 3 1 5
  • No. denitration catalyst described in Japanese is a substance known as a solid super acid.
  • the solid superacid is obtained by immersing sulfuric acid in a hydroxide such as zirconium, filtering and drying the hydroxide, and then calcining the hydroxide in advance.
  • the solid superacid is used as a carrier.
  • the denitration catalyst used in this method is troublesome in preparation of the denitration catalyst, such as preliminarily firing the support.
  • the catalyst for purifying exhaust gas of the present invention does not need to have a sulfated group supported by a solid super-strong acid; gold such as alumina)!
  • a sulfated group supported by a solid super-strong acid; gold such as alumina gold such as alumina
  • Exhaust gas purifying catalyst of the present invention by that it is a structure having the I Li Jiumu and sulfur, in the removal of N_ ⁇ x in an oxidizing atmosphere, show activity in a wide temperature area, on which heat resistance Because of its excellent durability, it can be effectively used for internal combustion engines such as diesel engines and lean-burn engines in which the exhaust gas becomes an oxidizing atmosphere and the temperature fluctuation range of the exhaust gas is wide. it can.
  • Another exhaust gas purifying catalyst of the present invention comprises a refractory inorganic compound carrying at least one element selected from the group consisting of platinum, palladium and rhodium, and a metal sulfate carrying iridium. It is a structure which has. According to the above configuration, the exhaust gas composition exhibits excellent exhaust gas purification performance over a wide range of compositions from a reducing atmosphere to an oxidizing atmosphere. Shows activity, and has excellent heat resistance and durability. For this reason, the above configuration is effectively used between internal combustion engines such as diesel engines and lean-burn engines in which the exhaust gas becomes an oxidizing atmosphere and the temperature fluctuation range of the exhaust gas is wide.
  • Still another exhaust gas purifying catalyst of the present invention is at least one kind of element selected from the group consisting of iridium, sulfur, calcium, strontium, and lithium as catalytically active substances. Due to the inclusion of the elements, the above-described structure shows higher catalytic activity for removing ⁇ ⁇ ⁇ in a wide temperature range under an oxidizing atmosphere, and has heat resistance and durability especially in a high temperature range. In addition, fluctuations in the optimum temperature of the exhaust gas exhibiting catalytic activity are suppressed, and the cost is low, so that it is excellent in practicality.
  • the above catalyst is effective for internal combustion engines such as diesel engines, in which the exhaust gas is in an oxidizing atmosphere, and the temperature fluctuation range of the exhaust gas is wide, and lean-lean engines and gasoline cylinder direct injection engines. It will be used for
  • Another exhaust gas purification method of the present invention is a method of setting the exhaust gas temperature at the inlet of the exhaust gas purification catalyst to 200 to 700 ° C.
  • the exhaust gas purifying catalyst is effective especially in the removal of NOx in an oxidizing atmosphere even when the temperature of the exhaust gas is low, so that the catalyst exhibits activity in a wide temperature range,
  • the exhaust gas used is a catalyst for competition, which has good heat resistance and durability.
  • the exhaust gas temperature is set low in order to improve combustion efficiency and improve fuel efficiency, and the exhaust gas becomes an oxidizing atmosphere, and the exhaust gas has a wide temperature fluctuation range. It is suitable for use in purifying exhaust gas from internal combustion engines such as engines, lean burn engines, and gasoline direct injection engines.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Biomedical Technology (AREA)
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  • Organic Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

Cette invention concerne un catalyseur d'épuration de gaz d'échappement comportant un substrat portant à sa surface de l'iridium en tant que matière d'activation du catalyseur, du soufre destiné à accroître l'activité de catalyseur de l'iridium et également du platine en quantité nécessaire. De préférence, le soufre est présent sous la forme d'un radical sulfate. Ledit procédé d'épuration des gaz d'échappement consiste à faire passer les gaz d'échappement issus d'un moteur à combustion interne à travers le catalyseur d'épuration, la température des gaz d'échappement au niveau d'un orifice d'admission du catalyseur d'épuration des gaz d'échappement étant fixée à une valeur comprise entre 200 et 700 °C. S'agissant de l'épuration des gaz d'échappement, la structure de catalyseur décrite ci-dessus est active à l'intérieur d'une plage de températures étendue, notamment en ce qui concerne l'élimination des oxydes d'azote dans une atmosphère oxydante, et ledit catalyseur présente une résistance thermique et une durabilité qui s'avèrent excellentes s'agissant de son aptitude au service.
PCT/JP1997/001211 1996-04-11 1997-04-09 Catalyseur d'epuration de gaz d'echappement et procede d'epuration correspondant WO1997037761A1 (fr)

Priority Applications (5)

Application Number Priority Date Filing Date Title
DE69738063T DE69738063T2 (de) 1996-04-11 1997-04-09 Katalysator und methode zur abgasreinigung
US08/973,684 US6214307B1 (en) 1996-04-11 1997-04-09 Exhaust gas purifying catalyst and exhaust gas purifying method
CA002223458A CA2223458C (fr) 1996-04-11 1997-04-09 Catalyseur et processus d'epuration des gaz d'echappement
KR1019970708846A KR100300825B1 (ko) 1996-04-11 1997-04-09 배기가스정화용촉매및배기가스정화방법
EP97916636A EP0832688B1 (fr) 1996-04-11 1997-04-09 Catalyseur d'epuration de gaz d'echappement et procede d'epuration correspondant

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JP08971696A JP3956158B2 (ja) 1996-04-11 1996-04-11 窒素酸化物除去用触媒
JP8/89716 1996-04-11
JP8/125162 1996-05-20
JP12516296 1996-05-20
JP8/320516 1996-11-29
JP32051696A JP3865838B2 (ja) 1996-11-29 1996-11-29 窒素酸化物除去用触媒、その製造方法及び該触媒を用いた排ガスの浄化方法
JP8/320531 1996-11-29
JP32053196A JP4330666B2 (ja) 1996-11-29 1996-11-29 排気ガス浄化用触媒および排気ガス浄化方法

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DE69738063T2 (de) 2008-05-21
EP0832688A4 (fr) 1999-08-18
CA2223458C (fr) 2002-06-18
CA2223458A1 (fr) 1997-10-16
EP0832688B1 (fr) 2007-08-29
KR100300825B1 (ko) 2002-02-28
US20010012502A1 (en) 2001-08-09
EP0832688A1 (fr) 1998-04-01
MX9710095A (es) 1998-10-31
DE69738063D1 (de) 2007-10-11
US6214307B1 (en) 2001-04-10

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